Total of 12 dives and already a few lessons and one almost "near miss"

[SapphireMind]

I was going to but I could have done the dives but chose not to because I was not in a great frame of mind. Also when asking for other dives during that week prior to the outting, their office DM recommended a 110' dive because I had my Nitrox as well. I mentioned it again about have 7 total dives and they said most likely a good choice not going if I didn't feel comfortable. All I wanted was an easy ocean dive and the whole thing went off the tracks with my shallow, Nursury reef dive getting cancelled because of lack of people signing up. If I'd have been fearless like it seems most people are I could have had a great learning experience by them allowing me to push my limits but unfortunately I'm a little conservative and kind of listened to the OW recommended limits which they told me was only a guideline and misunderstanding that they don't allow you to dive past 60'ish. I was at the point where I did not want to argue nor have them tell me it was my fault.

Isn't nitrox more appropriate for shallower, longer dives? I was taught that for depth dives, you do not want to use nitrox probably. Is this incorrect?

 

[MrBigfins]

Isn't nitrox more appropriate for shallower, longer dives? I was taught that for depth dives, you do not want to use nitrox probably. Is this incorrect?

Nitrox can be used for a variety of depths. What mix of nitrox you use is determined by the mod for the depth you plan. So for 110 you could plan 32% or 30% if there wasnt a hard bottom and you were worried about exceeding mod

 

[Marie13]

Isn't nitrox more appropriate for shallower, longer dives? I was taught that for depth dives, you do not want to use nitrox probably. Is this incorrect?

Good Lord, what are some of you people being taught? Just ran into someone on a FB group who said she wasn’t taught to analyze her own tanks in an Advanced Nitrox/Deco Procedures class.

You are incorrect. Nitrox can be used to extend bottom time on deeper dives, as well. 32% is one of the note common Nitrox mixes. It’s MOD is 111ft.

 

[MrBigfins]

Good Lord, what are some of you people being taught? Just ran into someone on a FB group who said she wasn’t taught to analyze her own tanks in an Advanced Nitrox/Deco Procedures class.

You are incorrect. Nitrox can be used to extend bottom time on deeper dives, as well. 32% is one of the note common Nitrox mixes. It’s MOD is 111ft.

Easy. She doesn't seem as if she has completed advanced nitrox. If she hasn't had experience with nitrox then it is most likely that voodoo fas to her. If all she heard was dont go too deep on nitrox, then she isnt wrong just not fully informed. Maybe help educate her instead of belittling her?

 

[Marie13]

Easy. She doesn't seem as if she has completed advanced nitrox. If she hasn't had experience with nitrox then it is most likely that voodoo fas to her. If all she heard was dont go too deep on nitrox, then she isnt wrong just not fully informed. Maybe help educate her instead of belittling her?

This was clearly AN/DP as 100% O2 was mentioned. Did I say I belittered her? No, just pointed out her instructor was very wrong and she needed to consider what else she might have been taught incorrectly.

 

[Protondecay123]

Did I say I belittered her? .

So what exactly is one doing when they belitter? Is this belittering?

Did I say I belittered ?

 

[MrBigfins]

This was clearly AN/DP as 100% O2 was mentioned. Did I say I belittered her? No, just pointed out her instructor was very wrong and she needed to consider what else she might have been taught incorrectly.

I was referring to your reply to Saphire. As far as the FB interaction, if she truly didnt know to analyze tanks by then advice for a new instructor was apt. I understand that your curt answer to Saphire was most likely based in your frustration from the other interaction with a somewhat experienced diver who should know better. However that wasnt Saphire minds fault and she isnt experienced based on her 0-24 dive count. So maybe a little more friendly advice or education on correct usage of nitrox?

 

[Storker]

Isn't nitrox more appropriate for shallower, longer dives? I was taught that for depth dives, you do not want to use nitrox probably. Is this incorrect?

There are several reasons for using nitrox, such as:

• For extending bottom time (but do make sure that you're within min gas requirements!)
• For reducing SI time
• For reducing N2 loading and decompression stress
• For reducing asymptomatic DCS, thus reducing post-dive lethargy (this is a really contentious issue, and there are strong opinions both pro and con this POV)

My strictly personal opinion: As long as you stay within the MOD of (currently) 1.4 bar pPO2, there are several upsides and hardly any downsides to using nitrox. Off the top of my head, the only downside I can think of is the effect it has on your wallet. And that effect may be anything between "zero" and "quite significant".

I'm well into middle age and not very fit. My current physical condition is definitely not what it was when I was in my 20s. Anything reducing my N2 loading and decompression stress is basically a good thing. So I've standardized on EAN32 as a breathing gas, particularly since I can get it for the same cost as I can get air.

 

[rvojr]

It was 110' to the sand so actual depth would have been 80-90' for most of it.

 

[BlueTrin]

Isn't nitrox more appropriate for shallower, longer dives? I was taught that for depth dives, you do not want to use nitrox probably. Is this incorrect?

So you should look at proper material to learn this but I’ll try to summarise:

The % of oxygen multiplied by the pressure in bars is called partial pressure of oxygen.

For example air is 21% oxygen or 0.21
At 30m the pressure is 4 bars.
So the partial pressure of O2, for normal air at 30m deep, is 0.21 x 4 = 0.84

Now you should avoid having more than 1.4 partial pressure for O2. If you go over you risk convulsions due to O2 poisoning your central nervous system.

110 feet is 33.5m which is 4.35 bars.

So you can calculate the maximum O2 percentage that would give you 1.4 partial Pressure for O2 by doing the following

1.4 / 4.35 = 0.32

This means that you are safe to 110ft if you have 32% or less of O2 in your mix.

So Nitrox 32 (which means 32% oxygen) is safe up to 110ft.

Why use Nitrox then ? Because when you remove some nitrogen and replace it with oxygen, you are absorbing less nitrogen and this will reduce the risk of decompression sickness and reduce the interval times as you have less nitrogen in your body.

You can dive longer and more often but not as deep as if you had less O2